Offscreen canvas rendering in proxy thread via ProxyingQueue

In our project we use the following build flags: "-sOFFSCREENCANVAS_SUPPORT", "-sPROXY_TO_PTHREAD" and try to do some gpu rendering it pthread but nothing is displayed. No errors in console. Our loop works via ProxyingQueue. When we switch loop to emscripten_set_main_loop our content is rendered successfully. If debug our code then content is rendered when stopped on breakpoint.
Is it possible to do offscreen rendering the way I've described?

**Version of emscripten/emsdk:**
3.1.24